Iron-free variable inductance.



No. 93,34o.

. PATBNTED JULY 14, 190s.

G. P.I MANSBRIDGE.

IRON FREE VARIABLE INDUCTANGE.

PPLIoATIoN rILD nume. 190e.

2 SHEETS-SHEET 1.

- l A Figi.

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yUNITED sn'rAir1'3sigENr OFFICE;

GEORGE FREDERICK MANSBRIDGE, or sANDERsTEADg ENGLAND.

IRON-FREE VARIABLE INDUCTANCE.

- onces, ofwhich the 4vfollowing 'is` especificaas distinguished from`v A tion.

trical coils the inductanceof wliichf-canbe readily varied or adjusted 'as may bedelsired, and which comprise'a station" coilfcarry-` ing member fand a-'in""' ica ym'ovabl coil-carrying member?- For tiesake Aof convenl ferred', in the'bod 'slof-,this'specificatiomto the embodiment o my invention in the form of instrument-whi,` comprises fourlf'clr'cl wirel mechanically? iot'in ded within separate -dis disk, theldisks-beingso mon axis that one diskic oils oneach v '0n a com'- be mechanically, cetro-magnetically, rotated relatively' to' the'blih'r; suitable elec'- trical connections being also provided.

The objectoftheinvention is' to increase the time-constant of the coils when4 used flor low inductance'values, to increase the range obtainable from anyone instrument, and to obtain a :more uniform' scale than can be obtained fromv similar. `instruments as at present made.`

' To this end I employr shallow coils which are of the largestl practicablel area, and some or all of which may be sectionallywound,'

set as nearly as possible flush with the surface of the disks, sc that when thewindings in one disk are immediately over'tho'se' 1n the other disk, they form -puctically one coil, and thus produce the maximum effect of combination or neutralization, depending upon whether the currents in ,the adjacent windings are in the same or in the opposite direction.

The accompanying drawings show, in Figure 1, a plan of an iron-free variable inductance constructed according topthis invention, yF' 2Y being a section on line 2 2 of Fig. 1. 3 is aI diagrammatic representation ofthe'electrical connections.

In Figs. l-and 2 of the drawings,.a is the stationary coil-carrying member, in the form of a disk, and b thc mechanically movable specmcuon of Lettera recent. y'applimai.mea umh 26,1906. serio Nb. scales.

This: invention relates to iron-free elec- 'respective y have re-f por fewe'ri'turns." In'FigjfQ the :lon coil is nas itherto'iconsjtructed,

4*the winding on 'the lower disk.

coil-carryingvmernbr, also in the form of ai' .disk,"Fig.'1 showing a convenient sha e for theco'ils c, whereby a central space d 1s leftV for the mechanical swiveling attachment e. In Fi 2 n1ay be seen the sectional winding of t e'coils c and a convenient section for them.

Patented July 14, '1908.

-As shown in Fig. 2 .the sectionalwinding is arranged as follows :#-The lower disk a carries a lon coil superposed b a'l short coil, while in't e up er disk b, a s ort coil isfsu-F perposed by a ong coil.' vIt is to be understood'v that the words,lon and-short I. aSn'lnvercin.used and as ap ied vto the coils "'areifmerel that the'jwindings are of greater showrifapproximately twice as thic vas the Ashort""coll'*iii-'order to indicate that it has' approximately: twice" the length and consequently""'t w efthe number. of ,turns, this permanently connected in series with thecoils l, l', which constitute the lon r section of he coils l', k' and l', are respectively connected to the terminals m and "n. -o 1s abr'ass 'strip for' connectinnr the terminals whereby tliewhole of the w1ndin y is-maile use of. By making connection with the terminals h and only, the sections f, f and 51,9',

are alone brought into use and this rendersl available a comparatively low range of ind uct ance, for example, from 1 to 10 millihenrys, but when the terminals j and m are joined together by the strip o, and connection is made with the .termina s and m. together los hand n, the whole of the windin'g is empio ed, and a 4comparatively .high range .of 1 i1 uctance is 'then available,

for example, from 10 to 100 millihenrys. B f I this arrangement it will be seen thatthe coi s j; and f, and k and k', although brought to separate electrical conneciirlms, form practi- .20 'vingt-betta 435,. x.- .asignadas adiiini,;i.obtain a practically using four ,A plecrcular ooilsfarrangedin pairs, AIiiise four sec ionally wound coils of apA 'A progngnately semi-rcircular-lform, arranged in airsl and ,withtheir straight sides adjacent. he best forg'thepiirpose is semi-circular but-mechanical,considerations,will not conveniently allo `fofth'e coils tbeing made-absolutely-semifcf l lar'. I mayv use'lialf-hexagon; half-octagori',131;A evenv lelliptical coils as,

, gittata. ,iesesec i .in ths.

ticable to the inner face of the disk so as to reduce to a minimum the distance between the faces of lthe coils in one @Lisi-tand* those on the other. 'I do not however-limit myself to the precise shape and section shown.

In certaui cases it is desirable that the electrostatic capacity of the system be as small as possible and to this end I wind and 'connect the coils so that a current flowing throu h them produces the minimum potentiati difference 'between the parts most closely adjacent one to anotherwhen' th'e instrument 1s adjusted to the lpisition of minimum' inductance.

I may, if desired,A employ sectionallxls@l wound circular coils.`. Also, in any one lmstruinent,.I may empio coils having a combin tion of simple anc'sectinal windings. Further, I may use semi-circular simple wound coils. u

- 1` .In'aniron-free variable inductance hav- 4ingjone stationi'iviy.coil-carrying 4member aml one mechanically movable coil-carrying niem- -bfenla vlurality of semi-circular Vshallow coils, init.E o i theseeoils being on Athe stationary member andj the remaining part on the mov- Q ablemembergf V2.I n an iron-free variable in ductance hav- P The tot (1)jb sing seini'fcircular'coilslwith their.`

uniforn'iscale' apdatthe saine vtime I increase the time-constant;-A fthe instrument since l stouteriywire .may be, used'lconse iicnt upon' d40"the,increased'spaceavailable." iirther, the' n n plamof brmgingthe sections to separate terminals perniitsof the instrument ieing used as a variable stan'rllard ol' either sell' oriniitual induction;y u -A Obviously thefplan may be. cmployedof' iisiiig'only Ytwo coils (simpleor sectionally wound), one on each disk,ibut ,this planning` volves the use of ii greater length of wire. for the same range. of imliictanr-e. By these means, without a great increase. of cost, I obtain (u) an inereasial range of indiictance, (li) a higher time-constant than can be obtainedv with eireiihircoils in instruments ofhthis type., ainl (el a practically uniform scale. 'Io obtain the highest iniliictance the coils` in eneh disk shoiihl be-iirrangci-i with their straight sides as eli-seI together as possible, but, in order toadol'pt. the well known and convenient method ol'4 swiveling.tlie'upper (il) disk'from its renter. as employed inginstriiments of this type, l shape the coils iii both disks in siieh :i inannei'l'hos to leave :i spa-ce at the renter wherein the sii'iveliilg attachment -ma be nimmteil. Further, thewinirlings in t', eaeh diskshiiild be arranged as close aspi'aeone mechanical y member, a plurality of sectionally-woiind ng'pone stationa coil-'carrying member and rnovab e lcoil carrying Asemi-circulan shallow coils, part of these coils being on the stationary member and the remaining part on the movable member. 3. In an iron-free variable inductancc having one stationary coil-carrying member and one mechanically movable coil-carrying mcniber,' the combination with the. stationar coil-carrying,r member, of semi-circular sha low coils carried thereby, semi-circular shal- -low coils carried by said movable member,

and means for connecting said members to-A gether so that the faces of the coils -in the. movable member may be mechanically moved over the faces of the coils in the stationary member.

4. ln an iron-free variable indiictance having one stationary coil-carrying member and one mechanically movable coil-carrying member, the combination with the, station` ary coil-carrying member of semi-rireiila-r shallow coils, wound in sections, carried thereby, semi-circular shallow coils, wound 'in'iuzctions carried by said movable member,

electrical connections so arranged that the said sections may be used singly or together, and means for connecting said members together so that. the faces of the coils in the movable member ma be mechanically moved ovcrjthc faces o the coils in the stationary member.

5. In an Viron-free. variable indiictaiice having one stationary coil-carr ing member and one. nwehaiiirally l movab c coil-carryingr member, the combinationfwith the statioliarr j A lofw coils wound in member, electrical coil-carrying member of semi-'circularfsh unequal sections carried thereby, semi-circularfshallow coils wound' in iinequal sections 'carried-,by .said movable connectionsy so arranged that the said Sectio "maybe used singly-or .f together, land-.'"means for connecting lsaidl members together 10"v sogthat the faces of the coils vin the I 'nov'able s member (ma -beme- :stationary member; and on the movable member.

7. In an iron-free variable inductaii'ce having one stationary coil-ca ingmember and one mechanically movalilse coil carrying member, a plura ity of, sectionally-wound tli'e remaining part shallow coils,- Wound 1n uneqal sections, part ',ofathese coils being on the stationary member [and tbefremaining part on themovable membelg-*and electrical connections so arranged `that" saidfsec 'ons may be nsed singly or toimmucxixANsBinDeE. 

